PPT 转 PPTX
把老版 PPT 演示文稿升级成 PPTX，这是现代 PowerPoint、Keynote 和 Google 幻灯片默认认可的格式。
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To
PPT
The legacy PowerPoint format from before 2007, still found in older slide decks.
PPTX
The modern PowerPoint presentation format, used by PowerPoint, Keynote, and Google Slides.